How To Fix /IWBEP/CM_CP105 - If-Match is requested but no ETag property was found

SAP Error Message - Details

• Message type: E = Error

• Message class: /IWBEP/CM_CP -

• Message number: 105

• Message text: If-Match is requested but no ETag property was found

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message /IWBEP/CM_CP105 - If-Match is requested but no ETag property was found ?

  The SAP error message /IWBEP/CM_CP105 If-Match is requested but no ETag property was found typically occurs in the context of OData services when a client attempts to perform an operation (like an update or delete) that requires an ETag for concurrency control, but the service does not provide an ETag for the resource being accessed.
  Cause:
  
  Missing ETag: The primary cause of this error is that the OData service does not return an ETag for the resource. ETags are used to manage concurrent updates to resources, and if the client sends an If-Match header expecting an ETag but the service does not provide one, this error will occur.
  Service Configuration: The OData service might not be configured to generate ETags for the entities being accessed.
  Entity Set Configuration: The specific entity set might not have ETag support enabled.
  
  Solution:
  
  Check Service Implementation: Ensure that the OData service is correctly implemented to return ETags. This typically involves checking the service's metadata and ensuring that the ETag property is included in the response for the relevant entity types.
  Modify Service Code: If you have access to the service code, you may need to modify it to include ETag generation. This can often be done by implementing the GET method to return the ETag in the response headers.
  Update Service Configuration: If the service is based on a framework like SAP Gateway, check the service configuration in the SAP Gateway Service Builder (transaction code SEGW) to ensure that ETag support is enabled for the relevant entity sets.
  Testing: After making changes, test the service to ensure that ETags are being returned correctly. You can use tools like Postman or SAP Gateway Client to inspect the response headers for the presence of the ETag.
  Client-Side Handling: If you are developing the client application, ensure that it correctly handles the absence of ETags. If the service does not support ETags, you may need to adjust your client logic to avoid sending the If-Match header.
  
  Related Information:
  
  ETag: An ETag (Entity Tag) is a unique identifier assigned to a specific version of a resource. It is used in HTTP to manage cache validation and concurrency control.
  OData Protocol: OData (Open Data Protocol) is a standard protocol for building and consuming RESTful APIs. Understanding the OData protocol can help in troubleshooting issues related to data access and manipulation.
  SAP Gateway: SAP Gateway is a technology that allows developers to create OData services for SAP applications. Familiarity with SAP Gateway and its tools (like SEGW) is essential for troubleshooting OData-related issues.
  
  By addressing the above points, you should be able to resolve the /IWBEP/CM_CP105 error and ensure that your OData service correctly handles ETags for concurrency control.